Grinding machine



Oct. 6, 1936. DNER I 2,056,182

GRINDING MACHINE 2 Filed Feb. 8, 1934 3 Sheets-Sheet 1 IIJUGWH? FmdeflloE Gardner 7m: 6

Oct. 6, 1936. E. GARDNER 2,056,182

GRINDING MACHINE Filed Feb. 8, 1934 I 3 Sheets-Sheet 2 Zahara? Frederic If dardvwv," GWx Man. 5.

Oct. 6, 1936. F. E. GARDNER GRINDING MACHINE 5' Sheets-Sheet 3 Filed F eb. s, 1934 I MXMc- 5.

Patented Oct. 6, 1936 UNITED STATES GRINDING MACHINE Frederic E. Gardner, Beloit, Wis., assignor to Gardner Machine Company, South Beloit, Ill., a corporation of Illinois Application February 8, 1934, Serial No. 710,214

Claims.

The invention relates generally to grinding machines and more particularly to a grinding machaine for finishing flat surfaces.

The general object of the invention is to provide a grinding machine in which the driven support for the grinding member includes means for magnetically drawing Work pieces against the grinding member.

Another object is to provide a grinding machine in which the grinding member includes magnetic material attracted by rotatable magnetic means and driven thereby.

A further object is to: provide a grinding machine of this character in which the rotatable magnetic means not only attracts the magnetic material in the grinding member and thereby causes said member to be driven, but also causes the work pieces to be magnetically drawn against the grinding member. 1

More specifically, the object is to provide a driving disk mounted on a rotatable driving shaft and having magnetic means embedded therein, and a grinding disk mounted on the driving disk and including magnetic material which is attracted by the magnetic means whereby the grinding disk is caused to rotate with the driving disk or mechanically fastened to the driving disk, the work pieces being attracted by the magnetic means and drawn against the grinding disk.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings, in

which:

Figural is a front elevational view of ,a machine embodying the features of the invention.

Fig. 2 is a fragmentary plan view of one form of grinding means.

Fig. 3 is an elevational view, partially in section, of the grinding means shown in Fig. 2.

Fig. 4 is a plan view of another form of grinding means.

'Fig. 5 is an elevational view, partially in section, of the grinding means shown in Fig. 4.

Fig. 6 is a. plan view of still another form of grinding means.

Fig. '7 is an elevational view, partially in section, of the grinding means shown in Fig. 6.

The preferred form of machine in which the invention is embodied is a vertical spindle disk grinder. This type of grinder comprises generally a hollow base It in which is mounted a vertical spindle H driven by means such as a pulley I2 and belt [3, the pulley being mounted at one side of the base H and carried on a horizontal shaft 14 extending into the base. The base. extends upwardly and its upper end is enlarged to surround a grinding member, indicated generally at :5, carried by, the upper end of the vertical spindle The invention is embodied preferably in a machine of this type and comprises generally a novel means for drawing the Work against the grinding member. Said means may also serve to establish a driving relation between the spindle I I and the grinding member. comp-rises a rotatable member mounted on the spindle for rotation therewith and including magnetic means by which work pieces of magnetic material may be drawn against the grinding member. When the rotatable member also serves to establish a driving relation between the spindle and the grinding member, the latter is so constructed as to include magnetic material which is attracted by the magnetic means in the rotatable member.

Both the grinding member and the rotatable member may have various specific embodiments. One form of grinding member and one form of rotatable member is shown in Figs. 2 and 3. The rotatable member shown therein comprises a supporting disk 20 fixed to the spindle l I and including magnetic means comprising, inthe present instance, a plurality of annular magnetic coils 2| embedded in the supporting disk 2i! and concentric therewith. The number of such coils depends upon the size of the disk, the purpose being to provide such coils as are necessary toproduce a magnetic field substantially coextensive with the grinding surface of the grinding member so that work pieces of magnetic material will be drawn I against said surface. In the present instance, two such coils are found to be suflicient to provide the desired field.

The grinding member I5 may be a disk made of the usual moulded abrasive material and preferably of the same size as the supporting disk 20, the member being glued or cemented to the front face of the supporting disk 20. Thus, when work pieces of magnetic material areplaced on the grinding surface, the magnetic coils 2| will draw the work pieces against said grinding surface.

A driving relation between the grinding member and supporting disk may also be established magnetically in addition to or instead of by the use of glue. For this purpose, finely divided particles of magnetic material such as iron may be included in the moulded material of the grinding member. Preferably the grinding disk is formed with annular portions 22 of the same diameters Briefly, said means as the magnetic coils 2|, and the magnetic particles are embedded in said portions.

In the embodiment of the invention shown in Figs. 4 and 5, magnets in the form of radially extending coils 23 are embedded in the driving disk 20, which provide a field substantially coextensive with the grinding surface to draw work pieces against said surface.

The grinding disk, in this form, comprises moulded abrasive material 24 to which is rigidly attached a thin backing plate 25 preferably of steel. Thus, the magnetic coils 23 attract the backing plate 25 of the grinding disk and cause the latter to be driven by the disk 20.

Figs. 4 and also illustrate a suitable work holder for grinding such articles as piston rings. This work holder comprises a pair of spaced bars 26 having notches 21 cut in their lower edges to guide the piston rings as they are moved across the grinding surface. It will be noted that the guide bars 26 extend across the grinding surface in a non-radial direction. Thus, because of the friction between the work pieces and the grinding disk, the rotation of the latter has a component which tends to move the work pieces along the guides 26. The magnetic attraction of the coils 23 for the work pieces will increase the pressure of the work pieces on the grinding disk, and hence will increase the friction therebetween, so that movement of the work pieces in their guides by the action of the grinding disk will be assured. This work holder obviously may be used with any of the forms of grinding disks shown herein.

The form shown in Figs. 6 and '7 is especially adapted for disks of large diameter. For disks of this size, preferably a larger number of magnetic coils are employed to provide a suitable magnetic field, four such coils, indicated at 30, being illustrated. The grinding disk for such size may be of the type in which a wire mesh 3| is embedded in the moulded abrasive 32 and secured to a steel backing plate 33 as by screws 34 threaded into nuts 35 embedded in the moulded abrasive 32. The steel backing plate 33 is magnetically attracted by the coils 30 and the grinding disk is thereby held for rotation with the supporting disk.

While certain forms of grinding disks have been illustrated in conjunction with certain forms of supporting disks and magnetic coils, it is to be understood that any of the forms of grinding disksmay be used with any of the forms of supporting disks herein illustrated. V

In connection with the forms herein illustrated, it is desirable to provide a pilot 36 on the supporting disk, which fits snugly intoa central hole 31 in the grinding disk. The pilot prevents the grinding disk from becoming miscentered by pressure of the work or other cause, and also maintains the grinding disk in proper position, should the electric current supplied to the magnetic coils be accidentally shut off while the disk is rotating.

In the operation of the grinding machine, the work pieces are placed upon the grinding surface of the grinding disk, and the field produced by magnetic coils draws the work pieces against said surface, thus relieving the operator of otherwise applying pressure on the work pieces. In those disks which include magnetic material, such as the disk shown in Figs. 2 and 3, which includes finely divided magnetic material, or the disks shown in Figs. 4, 5, 6, and 7, which include steel backing plates, the attraction of the magnetic field produced by the coils for the magnetic material in the grinding disk causes the disk to be driven by the supporting disk.

From the above description, it will be apparent that I have provided a grinding machine in which the support for the grinding member includes means for magnetically drawing the work against the grinding member. It will also be apparent that I have provided a grinding machine in which a grinding disk and the work pieces are both attracted by magnetic means car- .ried by the supporting disk whereby the grinding disk is caused to be rotated with the supporting disk and the work pieces are drawn against the grinding disk.

I claim as my invention:

1. A grinding machine comprising, in combination, a rotatable drive shaft, a supporting disk mounted on the end of said drive shaft and rotatable therewith, magnetic means embedded in said supporting disk, and a grinding disk carried by said supporting disk and including magnetic material attracted by said magnetic means whereby said grinding disk will be caused to rotate with said supporting disk.

2. A grinding machine comprising, in combination, a rotatably driven supporting disk, a grinding disk made of moulded material including abrasive and finely divided magnetically attractable material mounted on the face of said supporting disk, and magnetic coils embedded in said supporting disk attracting the magnetic material in said grinding disk for rigidly securing said grind disk to the supporting disk for rotation therewith.

3. A grinding machine comprising, in combination, a rotatably driven supporting disk, annular magnetic coils embedded in said supporting disk and concentric therewith, and a grinding disk mounted on the face of said supporting disk, said grinding disk being made of moulded material having annular portions of the same diameter as said coils in which finely divided magnetically attracted material is included in the moulded material.

4. A grinding machine comprising, in combination, a rotatably driven supporting disk, a grinding disk comprising moulded abrasive material and a backing plate made of magnetic material rigidly secured to the moulded abrasive material and mounted against the face of the supporting disk, and magnetic coils embedded in said supporting disk attracting said backing plate for rigidly clamping said grinding disk to the supporting disk for rotation therewith.

5. A grinding machine comprising, in combination, a rotatably driven supporting disk, a grinding disk comprising a disk made of moulded abrasive material, a backing plate made of magnetic material, a plurality of nuts embedded in the moulded material, and screws extending through the backing plate and threaded into said nuts for rigidly securing the backing plate and moulded disk together, said backing plate being mounted against the face of said supporting disk, and magnetic coils in said supporting disk attracting said backing plate for rigidly clamping said grinding disk to the supporting disk for rotation therewith.

6. A grinding machine comprising, in combination, a grinding disk mounted to provide a horizontal grinding surface, work guides extending across said grinding surface and so positioned that the friction of the work pieces against the disk will move the work pieces along said guides, and magnetic means for drawing the work pieces against the grinding surface to increase the grinding action of said disk on the work pieces and to increase the friction therebetween.

7. A grinding machine comprising, in combination, a rotatably driven supporting disk, a grinding disk mounted on the face of the supporting disk comprising a unitary rigid structure including abrasive material and magnetic material, and magnetic coils in said supporting disk attracting said magnetic material for rigidly clamping said grinding disk to the supporting disk for rotation therewith.

8. A grinding machine comprising, in combination, a rotatable driving member provided with an axially positioned pilot and having magnetic means rotatable therewith, and a grinding disk mounted on said driving member and including magnetic material attracted by said magnetic means for causing the grinding disk to rotate with the driving member, said grinding disk having an axial hole fitting snugly onto said pilot for maintaining the grinding disk in an axial position.

9. A grinding machine comprising, in combination, a rotatable driving member having magnetic means rotatable therewith, a grinding disk mounted on said driving member and including magnetic material attracted by said magnetic means for causing the grinding disk to rotate with the driving member, and cooperating means on said driving member and said grinding disk for holding said grinding disk axially positioned relative to the driving member.

10. A grinding disk for a grinding machine having a rotatable disk-supporting member provided with one or more concentric annular magnetic coils, said disk being made of moulded material having concentric annular portions of the same diameter as said coils, in which finely divided magnetically attractable material is included in the moulded material.

FREDERIC E. GARDNER. 

